1. Field of the Invention
The invention relates to an improved fuel injector for injecting fuel into an internal combustion engine.
2. Description of the Prior Art
An injector of the generic type with which this invention is concerned has been disclosed by German Patent DE 195 19 191 C2. In the subject of that patent, the piezoelectric actuator and booster piston are seated on the upper end of the injector body, and the force transmission to the nozzle needle, located on the lower end of the injector body, is effected via a long tappet. The tappet is in hydraulic communication with the fuel inflow. A pressure conduit machined into the injector body leads to the nozzle outlet. An annular chamber surrounding the tappet in its lower region is also provided, at which a fuel return conduit originates. The fuel return conduit communicates hydraulically with an inner chamber, extending above the tappet, of the booster piston. A control chamber embodied below the booster piston is supplied from the fuel inflow via a leakage gap surrounding the tappet in the injector body.
The known injector is complicated in its construction, is composed of a comparatively large number of components, does not meet the stringent demands made of modem fuel injection systems, in particular common rail systems for diesel engines.